Well done. In all modesty, you forgot to mention that you also found the sizes for the aplanatic doublet (which Grubb claimed was purloined by Dallmeyer re. the RR!) which appears to be very rare.
But I don't understand why all the Grubb aplanatics we have found, have such low numbers if they were still available in the 1880's?

The new "A", c/o Peterloy, looks like the same size (proportions) as my "A".

A bit more information about Grubb is that the original London agent for Grubb at the start of the 1860's was (Israel) Joseph Solomon of Russell Square who ceased trading around 1872. Perhaps Watson took over the agency at this time?